IEC 61331:2014 applies to materials in sheet form used for the manufacturing of protective devices against X-radiation of radiation qualities generated with X-ray tube voltages up to 400 kV and gamma radiation emitted by radionuclides with photon energies up to 1,3 MeV. This Part 1 is not intended to be applied to protective devices when these are to be checked for the presence of their attenuation properties before and after periods of use. This Part 1 specifies the methods of determining and indicating the attenuation properties of the materials. The attenuation properties are given in terms of:- attenuation ratio;- build-up factor; and- attenuation equivalent together with, as appropriate, an indication of homogeneity and mass per unit area. Ways of stating values of attenuation properties in compliance with this part of the International Standard are included. Excluded from the scope of this International Standard are the methods for periodical checks of protective devices, particularly of protective clothing, the methods of determining attenuation by layers in the radiation beam, and the methods of determining attenuation for purposes of protection against ionizing radiation provided by walls and other parts of an installation. This second edition cancels and replaces the first edition of IEC 61331-1, published in 1994. It constitutes a technical revision. This second edition has been adapted to apply to the present technology. In particular, this second edition is consistently applicable to lead- and non-lead-containing materials. The essential changes and extensions are:- the extension of the scope to cover photon-emitting radionuclides;- improved methods to determine the attenuation ratio;- the addition of the so-called inverse broad beam condition;- the addition of a method to calculate the attenuation ratio of photon-emitting radionuclides;- the definition of new standard X- and gamma radiation qualities used for testing;- the addition of the so-called lead equivalent class; and- tables of attenuation ratios, build-up factors and first half-value layers for the standard radiation qualities filtered with different thicknesses of lead.